


arbitrary applications of equivalent exchange

by intentandinvention



Category: Fullmetal Alchemist: Brotherhood & Manga
Genre: Awful Ones Because Ed, Fluff, Happy Ending, M/M, Peripheral Ed/Winry, Polyamory Negotiations, Post-Brotherhood
Language: English
Status: Completed
Published: 2018-01-22
Updated: 2018-01-22
Packaged: 2019-03-08 07:43:34
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,742
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13453620
Author URL: https://archiveofourown.org/users/intentandinvention/pseuds/intentandinvention
Summary: Ed grins, and it’s like the sun coming out, and Roy swore to himself that he’d stop thinking about Ed like this but he’d underestimated the way that Ed draws him in, ever since he suddenly grew up. This is why they haven’t seen each other for so long: Roy’s got very good at making excuses. Ed is clearly deeply in love with Winry – and even if he wasn’t, he doesn’t need a half-blind war criminal near twice his age ogling his ass.





	arbitrary applications of equivalent exchange

**Author's Note:**

> Er. This is not normally my fandom, and I have a lot of other stuff going on, but this is Important.

The first time it happens is, confusingly enough, on Edward’s wedding day.

Ed’s been married to Winry for three hours, and Al’s been keeping everyone’s glasses topped up because somewhere in between saving the world and revolutionising both alchemy and alkahestry he learned to host like a demon, and Ed’s cheeks are a little red and he laughs easily when he’s tipsy, and he looks _so happy_.

Roy, who has managed not to think about how incandescently gorgeous Ed is in that particular suit for nigh on two whole minutes, has beat a quiet retreat to the backyard of the Rockbell house claiming to need some air, accompanied by Riza and Miles. The three of them see each other several times a week even now that Ishval is starting to stand on its own, but for some reason they’ve still sought each other out to talk shop, even at Edward’s wedding. Not, Roy reflects as Riza and Miles start discussing the new friezes commissioned for the rebuilt Temple, that it feels like work anymore. The massive, region-wide project that he’d started from his hospital bed and continued with Fuhrer Grumman’s blessing — and eventually, the Ishvalans’ as well — has become his life, not just his job.

The first few years had been… difficult, to say the least. Roy may have helped to save Amestris, but if anything that had proved how little he’d done for Ishval, and many of the refugees who had returned to the rebuilding had lost family and friends in the flames – others had burn scars, or had lost limbs, and more than once Roy had been both grateful and made utterly wretched by the fact that with his sight stolen by Truth, he’d been unable to see the damage he’d dealt. Blind but still fully capable of creatively interpreting every suggestion that he retire, he’d relied on Riza and the rest of his team to interpret reports for him and to keep him safe in the ruins of Ishval. The final remaining Philosopher’s Stone had been given into Scar’s care, pledged to Ishval’s defence, whilst Roy did his best to make sure that it would never be needed.

Once the Ishvalans had drawn up new city plans, Roy had worked with the other State Alchemists to bring down the ruins and level the ground, although he’d been worse than useless for construction. He’d retreated to administration then, negotiating trade, forming an Ishvalan military police division, and continuing to spread the word that Ishval was being rebuilt.

Towards the end of the third year, Scar had come to East City, along with three other Ishvalan elders and, confusingly, Alphonse Elric, taller than Roy remembered and with a voice that must have broken during his long travels in Xing and beyond. The Ishvalan elders had spoken first, and when Roy had understood what they were offering, what they could _give_ him, he’d been simultaneously deeply honoured and completely horrified. His sight, in trade for the souls of Ishvalans he could well have killed himself?

He’d told them no — save the stone to use for Ishval.

It had gone quiet then, in that way it did when sighted people were exchanging expressions that he couldn’t see, although Riza had remained still by his side so he’d known he was in no danger. But then Alphonse’s voice had sounded from in front of him, the young man leaning over his desk.

‘General Mustang? This _is_ for Ishval. The Ishvalans aren’t stupid; older and wiser heads than ours have discussed it at length. It’s even been communicated to the souls still in the stone, who have agreed to it. The Ishvalans know that you and Brigadier General Armstrong are the only ones consistently advocating for Ishvalan reintegration, that most of the Amestrian High Command is still openly against it. They also know — and forgive me for saying this, but Fuhrer Grumman agrees with me that it’s true — they know that Amestris as it is now will never accept a blind man as Fuhrer, and it certainly won’t accept an Ishvalan. So with all due respect, General, kindly sit back, shut up, and let me use what’s left of the Stone to give them back their best hope of a peaceful future.’

There hadn’t been much Roy could say to that.

So he’d done as he was told, and after three years of utter darkness he’d opened his eyes to see the blurred last light of Ishval’s Philosopher’s Stone as it crumbled into dust in Al’s equally blurred hand. It had turned out that there wasn’t enough power left in the Stone to completely restore his sight, but after three years of blindness Roy was prepared to concede that he looked pretty good wearing glasses, even if he was a little sad that Maes wasn’t there to laugh himself sick after all the times Roy had made fun of his.

And so. Here they are. And here’s Ed, sauntering up with a glass of champagne, dazed and impeccably dressed and happy, like something from one of Roy’s more socially acceptable fantasies. The conversation stops whilst Miles gives his congratulations and Roy and Riza, who’ve already spoken to Ed, exchange an amused glance at the way the young man’s eyes practically glow when he replies that yes, Winry looks _incredible_ in her wedding dress.

Miles is about to say something else when there’s a call for him from the front yard, an Ishvalan colleague asking to clarify some point or other, and Miles nods to the three of them and excuses himself. Ed turns to Roy, and Roy is definitely imagining the once-over the man gives him, but it ties his tongue for an instant too long before Riza jumpstarts the conversation again.

‘So, Ed, are you enjoying being a married man?’ she asks, a slight teasing in her voice.

Ed grins, and it’s like the sun coming out, and Roy swore to himself that he’d stop thinking about Ed like this but he’d underestimated the way that Ed draws him in, ever since he suddenly grew up. This is why they haven’t seen each other for so long: Roy’s got very good at making excuses. Ed is clearly deeply in love with Winry – and even if he wasn’t, he doesn’t need a half-blind war criminal near twice his age ogling his ass.

Roy resettles his glasses self-consciously, and catches Ed’s eyes sliding back to Riza as he talks about how disbelievingly happy he is, how beautiful Winry is today but also yesterday and every day he wakes up beside her, how wonderful it is to have everyone celebrating with them. Not that Ed is technically celebrating with everyone, because everyone _else_ is in the front yard or the marquee out in the front field, but Ed conveniently ignores that fact.

‘You look fantastic today,’ Ed says suddenly. Roy opens his mouth to agree with him – Riza is frankly stunning in her understated navy blue dress – but abruptly realises that it’s _him_ Ed’s looking at. All of his carefully practised wit fails him: he doesn’t know what to say to this, to Edward Elric telling him he looks good, to Edward Elric _looking_ at him like that, openly appreciative. And Riza isn’t saying anything, she’s just nodded a little, the utter traitor.

Finally, Roy gathers his wits. ‘Thank you,’ he says carefully, just about managing not to make it into a question. ‘You as well.’

And it’s a perfectly normal thing to say, complimenting the groom on how well he cleans up on his wedding day despite a tendency to wander around in half-torn shirts and too-tight pants the rest of the time, but somehow Roy suspects that most people don’t say it whilst thinking about how the groom’s collarbones look alarmingly lickable now he’s discarded his bow tie and opened his shirt collar, or how mesmerising the flecks of brown in his eyes are, or how the golden hair he’s tied back into his now-customary ponytail would look amazing trailing over white sheets….

Ed is suddenly close, closer in fact than he’s been since Roy punched him in the face in an alleyway four years ago, and before Roy can process much more than that he’s grown taller in the last few years, Ed is _kissing_ him.

And it’s not just a gentle peck on the lips, either: Ed’s mouth is open, and his tongue trails along Roy’s lip, and Roy is utterly, completely helpless to do anything against the inexorable joy in his heart except close his eyes and _let him in_. Ed’s fingers are clenched on Roy’s lapels and Ed’s tongue is in his mouth and Ed’s lips are full and soft and dry and Ed _wants_ this, and Roy can’t do anything except give it to him, mouth and heart and anything and everything else he has. He sinks himself into the indescribable softness of Ed’s mouth, savouring every sensation that he knows he’ll never have again and shouldn’t have now, but this is Ed and Roy can’t deny him anything, has honestly never been physically capable of it, never mind that this is so immensely _not okay_ , and Riza is going to be awfully sarcastic about it all, and Roy should step back right now, he should leave the whole wedding and never come back to Resembool in his life ever except that that would mean stopping this kiss.

Of which he is wholly, devastatingly incapable.

Roy tells himself all of this, but when Ed draws back, hands smoothing over the creases in Roy’s lapels (but _doesn’t move_ _away_ , Roy’s brain burbles from its dizzy heights), he can’t make himself regret it.

He opens his eyes, and can only stare down into Ed’s golden ones, and can barely think, let alone work out what to say.

Ed, who looks if possible even happier than he did when he came to find them, whose lips are gleaming, whose face is bright red, runs his hands down Roy’s chest one last time. He pats the lapels smooth and grins before he turns on his heel and dashes down the garden path towards the gate, flinging ‘See you later!’ over his shoulder like a lifeline, which is immensely fitting because Roy is so terribly and inextricably lost at sea here.

To his horror, Roy realises that _Winry is standing at the gate_ , although she is at least looking over to the marquee rather than into the back yard. Ed slips his arm around her waist and kisses the tip of her nose, and she’s smiling and Roy doesn’t have a wrench-shaped bruise on his face, so maybe she didn’t just see her husband with his tongue in another man’s mouth on their wedding day?

The apparently happy couple wander back into the front yard, leaving Roy and Riza alone.

Roy doesn’t smoke, but he’s seriously wondering if he can summon the co-ordination to raid the stash that Havoc keeps in his wheelchair. It’s some time before he manages to speak.

‘Captain, what–’ he begins.

‘Edward just kissed you, sir,’ Riza interrupts thoughtfully, and apparently without judgement. ‘Quite enthusiastically, and with his new wife watching from a discreet distance. Winry saw the whole thing with no sign of surprise, sir. However, Alphonse is making his way over here, so might I suggest that you reassemble your brain for strategic thought and sort out the situation in your pants before he’s within shouting distance?’

Ah, right.

‘Remind me to promote you again, Captain,’ Roy murmurs, and fortunately the sight of a genial Alphonse Elric on the approach inspires quite enough terror for the “situation” in his pants to near resolve itself. Hardened criminals have been known to flee from that sunny smile.

Except, Ed _kissed_ him.

Enthusiastically, as Riza has put it so tactfully.

And Winry watched, apparently, which – _no_ , not the time for it, not when Alphonse’s eyes are slightly narrowed and his head a little tilted as he looks Roy up and down, for all the world as if he’s a little surprised not to see a sign saying “Property of Edward Elric”. And no, that train of thought is _not helping_. Roy has been informed by several high-ranking military officers that he has one of the finest strategic minds in all of Amestris, but apparently the enemy has never been quite as terrifying as a nineteen-year-old alchemy prodigy. And outstanding martial artist, said strategic mind adds glumly.

‘Hello, Alphonse,’ Riza says, and Alphonse turns from his inspection of Roy to smile at her.

‘Hello, Captain,’ he says, and he sounds genuinely cheerful, so perhaps he doesn’t mean to murder Roy for kissing his brother. Not, of course, that Roy presumes that he’d find out if Alphonse planned to murder him before it actually happened. ‘Might I borrow the General for a moment?’

On second thoughts, Roy isn’t going to see another sunrise.

But Riza, who is beautiful and perfect and capable and deserves a pay rise, rests her hand on Roy’s arm and asks the question Roy can’t quite vocalise right now. ‘Actually, we were hoping you might explain to us exactly what’s going on.’

Alphonse grimaces, and Roy might just make that sunrise after all. ‘I’m very sorry about that, General,’ he says, and he actually sounds a little awkward. ‘He doesn’t drink often and –’ Roy feels his face go wooden as his almost-emerged yet wholly-inadvisable hopes wither and die— ‘we’ve talked about the best way to do things and obviously ambushing you whilst somewhat tipsy was definitely _not_ in the top five–’

Wait.

‘You’ve _talked_ about – about _what_ , exactly?’ Roy finds himself asking, without any apparent input from his brain.

Alphonse frowns. ‘He… didn’t say anything?’

‘He kissed Roy extremely thoroughly, said “See you later” and then left rather abruptly,’ Riza replies.

Roy may still be reeling a little from that first phrase being a thing that actually happened. Ed _kissed him_.

Alphonse takes a deep breath, closing his eyes. ‘I am so, _so_ sorry, General,’ he says to Roy, and oddly enough he actually sounds it. Logically speaking, Roy supposes that there must be people who would object to being kissed extremely thoroughly by Edward Elric, and it’s probably rather nice of Alphonse to assume that he’s one of them. ‘Would you excuse me? It appears that I need to have a chat with my brother.’

And with that he’s gone, and Roy’s lips are still tingling because _Ed kissed him_ , and he has absolutely no idea what just happened, but he’s never going to forget a single confusingly-ecstatic second of it.

Except, he is, because Ed is happy. He has no right to ruin that. He will not be party to ruining that.

So he leaves as soon as is polite, giving a carefully blank goodbye to the happy couple and using his best escape and evasion training to stop Alphonse from intercepting him on his way out. Somewhat to his shock, Riza lets him go.

 

It’s been a whole two Elric-less months since the wedding when his office door opens and Alphonse strides in, towing his brother, whom he places in the chair opposite Roy.

‘There is going to be a _discussion_ ,’ Alphonse says darkly, and he leaves. The lock clicks behind him.

Roy wasn’t actually aware that Ed’s face was capable of matching his old jacket quite so perfectly. Ed’s refusing to meet his eyes, but it's not _Roy's_ brother who's locked them in the office and this is not Roy's situation to explain, so Roy goes back to his work. Ed rarely reacts well to being pushed, and anyway Roy has a lot of reports to get through. He can be casual about this.

He’s halfway through the restructuring report for the Ishvalan police when Ed pushes out of the chair and starts pacing the carpet. Well, Roy’s worked in more distracting environments. He puts his head down, pushes his glasses back up his nose, and concentrates on districting proposals.

‘I proposed to Winry with equivalent exchange, did you know that?’ Ed says after a while.

The words drag Roy rather abruptly out of his reading. This is a conversation he wants to pay attention to, wants to go _right_ , and his heart’s suddenly faster. _Casual,_ he reminds himself.

‘Is this a test to see if I remember Al’s speech at the wedding?’

‘Oh yeah, I forgot,’ Ed concedes, and he meets Roy’s eyes for just a moment, then looks away again, still a little bit red. ‘But yeah, I did. Couldn’t figure out how else to say it, it wasn’t like I exactly had any role models for romantic relationships, right? So I said I’d give her half my life if she gave me half of hers, and, uh, she laughed at me. And it took me a few months to figure it out and stop trying to calculate the exchange, but she was right, obviously, because you can’t give someone half your life like it’s some kind of pie, like she gets half my hours and I get the other half and we end up even. Because even when I’m on the other side of Xing she’s still got all of it, right? Just like when she’s locked in her workshop for three days and I only see her at mealtimes, I’ve still got all of hers. I’m hers, she’s mine, but we’re still our own as well. No equivalent exchange, it goes out the window, you know?’

Honestly, Roy doesn’t know – there’s a reason he’s never married, and also it’s an extremely odd feeling, being so glad that Ed has someone who makes him feel this way but then gently regretful that it isn’t him, all wound through with shards of utter guilt because regardless of how Winry seems to feel, she can’t possibly be happy about all of this. Also, Ed’s not improved on his tendency to ramble. But he nods, because Ed’s doing that thousand yard stare where he’s working out what to say and knows he’s going to get it wrong anyway.

‘But then, if equivalent exchange doesn’t apply, then there aren’t any restrictions, right? I mean, uh, other than, y’know—’ and here Ed goes a _blazing_ red, and Roy raises an eyebrow and ignores the deep temptation to dig whilst Ed rallies magnificently— ‘ _Anyway_ , why should I only be able to give all that to only one person? Who figured out that rule, and where’s their data and how sure are we that their methodology isn’t outdated, and people as variables is fucked anyway unless you just think of people as _energy_ instead of people, so how can you possibly know unless you try, and also what sort of alchemist just takes a hypothesis as given without testing it themselves? And I might not technically be an alchemist any more, but I still think like one, and also, Al agrees.’

He looks triumphant, as if Al agreeing settles everything, and his pacing somehow stops directly in front of Roy’s chair. Roy, who _thinks_ he’s following, and whose heart is in his mouth at what he thinks Ed just said, would like to agree as well, but he’s a politician as well as an alchemist, which means he needs to know exactly what he’s agreeing to first.

But then Ed frowns, and looks horrified.

‘Hang on, though. Me and Winry, that’s fine, we give everything and we get everything back, so there’s sort of equivalent exchange there anyway, and we live together and we share everything. But you— that’s not fair, you wouldn’t have any of that. I mean obviously if you found someone else like I’ve got Winry, I wouldn’t— but you don’t have someone like that, and I can’t be that because Winry, but then I might mess up your chances of finding—’

Roy might actually cry if Ed talks his way out of this on the basis that it would be _unfair to Roy_. He stands up, needing to be on the same level as Ed for something this important, and stops himself from reaching out. Ed’s scowling at the floor, fists clenched, and Roy swallows, and reverts to habits that he’s pretty sure are ingrained in both of them.

‘Edward, could you debrief me on that, please?’ he asks carefully.

Ed rolls his eyes at Roy’s toes, telegraphing charmingly familiar exasperation. ‘Keep the fuck up, Mustang,’ he says, but there’s no venom in it, only aching resignation. ‘Doesn’t matter if Winry says it’s fine: even without equivalent exchange, I can’t just expect you to be okay with being my bit on the side for the rest of your life.’

Somewhere in the back of his head Roy’s fairly certain that that’s the least romantic thing he’s ever heard, but it seems to be having a significant effect on him anyway if the way that his heart seems to be trying to burst out of his chest is any indicator. Maybe ordinary romantic standards don’t apply to Ed.

‘But what if I am?’ he manages.

Ed’s head jerks up, his eyes widening and then narrowing, but Roy presses on, not sure he can stop himself talking anyway now that he’s said that, now that he’s jumped in with both feet and the water’s closing over his head.

‘That is to say, I’d rather you didn’t think of me as a “bit on the side” because that implies a certain degree of casual indifference I’m really not sure I can endure, let alone reciprocate, and whilst I have no immediate reservations regarding a lifelong commitment I feel it’s important not to underestimate the value of flexibility in any plan of action – but those minor issues notwithstanding, and with Winry’s blessing, and all other arbitrary applications of equivalent exchange and expectations aside, Ed…’ Roy forces himself to take a breath, eyes now locked with Ed’s, which are impossibly intense, ‘I would very much like to be in a relationship with you. If that’s what you want.’

And there’s an awful, endless moment when Ed doesn’t say anything, and Roy wonders if he’s somehow managed to get this completely and terribly wrong, and then Ed bites his lip, his frown fading.

‘No casual indifference,’ Ed says, and he’s suddenly grinning now, almost blinding. ‘Got it. Now we’ve got that out of the way, will you please kiss me?’

Roy reflects on certain things never changing, and does as he’s told.

**Author's Note:**

> Comments and kudos are always welcome encouragement. If you want to give me a prompt or ramble about meta, poke me on [tumblr](http://intentandinvention.tumblr.com)!


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